1,748 research outputs found
Thermodynamics of the Mg-B system: Implications for the deposition of MgB2 thin films
We have studied thermodynamics of the Mg-B system with the modeling technique
CALPHAD using a computerized optimization procedure. Temperature-composition,
pressure-composition, and pressure-temperature phase diagrams under different
conditions are obtained. The results provide helpful insights into appropriate
processing conditions for thin films of the superconducting phase, MgB2,
including the identification of the pressure/temperature region for
adsorption-controlled growth. Due to the high volatility of Mg, MgB2 is
thermodynamically stable only under fairly high Mg overpressures for likely
growth temperatures. This constraint places severe temperature constraints on
deposition techniques employing high vacuum conditions
Interaction-induced anomalous transport behavior in one dimensional optical lattice
The non-equilibrium dynamics of spin impurity atoms in a strongly interacting
one-dimensional (1D) Bose gas under the gravity field is studied. We show that
due to the non-equilibrium preparation of the initial state as well as the
interaction between the impurity atoms and other bosons, a counterintuitive
phenomenon may emerge: the impurity atoms could propagate upwards automatically
in the gravity field . The effects of the strength of interaction, the gradient
of the gravity field, as well as the different configurations of the initial
state are investigated by studying the time-dependent evolution of the 1D
strongly interacting bosonic system using time-evolving block decimation (TEBD)
method. A profound connection between this counterintuitive phenomenon and the
repulsive bound pair is also revealed.Comment: 4.1 page
Floquet Majorana fermions in driven hexagonal lattice systems
We propose Floquet chiral topological superconducting systems hosting Floquet
Majorana fermions, which consist of hexagonal lattices in proximity to
superconductors with shining circularly polarized light. Specially for bilayer
graphene system, we demonstrate that there exist three topological phases
determined by certain parameters, namely, the amplitude and frequency of the
induced light. The number of chiral Floquet Majorana edge states is confirmed
by calculating Chern number analytically and energy spectrum in ribbon
geometry. Moreover, this proposal is generalized to other hexagonal lattice
systems, such as monolayer graphene and silicene. Notably, the parameter range
of induced light to achieve the chiral Floquet Majorana edge states is
experimentally feasible, and the corresponding Floquet Majorana fermions can be
probed based on differential conductance using scanning tunneling spectroscopy.Comment: 9 pages, 8 figure
Inferring cellular regulatory networks with Bayesian model averaging for linear regression (BMALR)
Bayesian network and linear regression methods have been widely applied to reconstruct cellular regulatory networks. In this work, we propose a Bayesian model averaging for linear regression (BMALR) method to infer molecular interactions in biological systems. This method uses a new closed form solution to compute the posterior probabilities of the edges from regulators to the target gene within a hybrid framework of Bayesian model averaging and linear regression methods. We have assessed the performance of BMALR by benchmarking on both in silico DREAM datasets and real experimental datasets. The results show that BMALR achieves both high prediction accuracy and high computational efficiency across different benchmarks. A pre-processing of the datasets with the log transformation can further improve the performance of BMALR, leading to a new top overall performance. In addition, BMALR can achieve robust high performance in community predictions when it is combined with other competing methods. The proposed method BMALR is competitive compared to the existing network inference methods. Therefore, BMALR will be useful to infer regulatory interactions in biological networks. A free open source software tool for the BMALR algorithm is available at https://sites.google.com/site/bmalr4netinfer/
Measuring TGF-β Ligand Dynamics in Culture Medium
TGF-β plays an important role in a myriad of cell activities including differentiation, proliferation, and growth arrest. These effects are influenced by the concentration of TGF-β in the surrounding milieu, which is interpreted by mammalian cells and subsequently translated into meaningful signals that guide their proliferation, survival, or death. To predict cellular responses to TGF-ß signaling based on molecular mechanisms, it is important to consider how cells respond to different ligand doses and how variations in ligand exposure impact Smad signaling dynamics and subsequent gene expression. Here we describe methods to measure TGF-β concentration in the environment and approaches to perturb cellular TGF-β exposure to gain a quantitative understanding of signaling dynamics of this pathway
Ground state and edge excitations of quantum Hall liquid at filling factor 2/3
We present a numerical study of fractional quantum Hall liquid at Landau
level filling factor in a microscopic model including long-range
Coulomb interaction and edge confining potential, based on the disc geometry.
We find the ground state is accurately described by the particle-hole conjugate
of a Laughlin state. We also find there are two counter-propagating
edge modes, and the velocity of the forward-propagating mode is larger than the
backward-propagating mode. The velocities have opposite responses to the change
of the background confinement potential. On the other hand changing the
two-body Coulomb potential has qualitatively the same effect on the velocities;
for example we find increasing layer thickness (which softens of the Coulomb
interaction) reduces both the forward mode and the backward mode velocities.Comment: 12 pages, 13 figure
The Universal Edge Physics in Fractional Quantum Hall Liquids
The chiral Luttinger liquid theory for fractional quantum Hall edge transport
predicts universal power-law behavior in the current-voltage (-)
characteristics for electrons tunneling into the edge. However, it has not been
unambiguously observed in experiments in two-dimensional electron gases based
on GaAs/GaAlAs heterostructures or quantum wells. One plausible cause is the
fractional quantum Hall edge reconstruction, which introduces non-chiral edge
modes. The coupling between counterpropagating edge modes can modify the
exponent of the - characteristics. By comparing the fractional
quantum Hall states in modulation-doped semiconductor devices and in graphene
devices, we show that the graphene-based systems have an experimental
accessible parameter region to avoid the edge reconstruction, which is suitable
for the exploration of the universal edge tunneling exponent predicted by the
chiral Luttinger liquid theory.Comment: 7 pages, 6 figure
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